2022 NHCA Annual Virtual Conference

Substantial hearing losses have been observed among Service Members firing M777 Howitzer cannons, especially after deployments with repetitive fire missions. The study to be presented, referred to as Characterization of Acute Short-term Military Population Auditory Shifts (CHASMPAS), has extensively measured both noise exposures and hearing performance during numerous live-fire exercises with the M777. Here we will present detailed data on the M777 acoustic environment, including the results of advanced noise-dosimetry technology and blast over-pressure measurements, coupled with documentation of the type and quantity of munitions fired during each exercise and descriptions of the administrative and engineering controls in use. Results of auditory function tests will also be presented, along with longitudinal data from medical records. We will close with a discussion of how these data may be used to improve estimates of noise hazards in operational settings, identify opportunities for additional prevention efforts, and unravel the dose-response relationship between noise and hearing loss.